The cart is not working as it should and I'd be loosing 80% of willing buyers like this!

I am using the Marketpress-plugin, FrameMarket/Gridmarket-theme
I have setup WPML also.

Sofar I am using two languages: German and Dutch (no English sofar!)

problem description:

when a user has added products (please add one with variation)
to see the whole drama:

1. When you click on the "view Cart"(Mein Einkaufswagen=my string-translation to german of "show cart") on the Top-Left, the cart will appear.
Alright, sofar as it shows product & variation: product/variation
But, when you hover over the checkout(Zur Kasse) button on the right-bottom side of the sliding-cart, it still points at http://cool-steam.com/store/shopping-cart/
with the result: Not Found...Sorry we could not find that page.

Guess that 80% would hook off here.

2. Only when I refresh the page (or click on "Mein Einkaufswagen" again), the correct link to respective languages carthttp://mydomain/store/einkaufswagen/
will appear, but also at the same time the variation has vanished & only "reappears" on respective "http://mydomain/store/order-status/" page or mail confirmation..

I changed the Products > Store Settings > Presentation > Shopping Cart Page to /store/einkaufswagen/ alright, but the problem still stays mainly the same:
The checkout button now (in every language) points athttp://cool-steam.com/store/einkaufswagen/
with the result, that at least a shopping cart is found, but always the one in the main language.
e.g. a Dutch customer will always see the checkout-process in German...
to better explain, I've added a screenshot.
To replicate you already have the access data to the site, and any developer may ask them from you.
Thanxx

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